Method and apparatus for producing a hollow body from a helically wound strand

ABSTRACT

A method and apparatus for forming a hollow, generally tubular, body of noncylindrical shape from a helically wound strand of a material which will firmly bond to itself upon contact, e.g. a thermoplastic. The strand is continuously deposited, onto and in contact with the last helical winding of the hollow body as the body is being continuously and simultaneously rotated and moved along its longitudinal axis, and the radial distance from the horizontal axis of the hollow body of the point of contact between the deposited strand and the last helical winding is gradually varied in accordance with the desired shape of the body. Simultaneously, the speed of rotation of the hollow body is varied in accordance with the variation of the radial distance of the contact point to maintain the peripheral speed at the contact point constant. A number of specific embodiments of apparatus for forming a body in this manner are disclosed.

United States Patent [19] Arnold 51 Feb. 27, 1973 METHOD AND APPARATUS FOR PRODUCING A HOLLOW BODY FROM A HELICALLY WOUND STRAND [76] Inventor: Wolfgang Arnold, Sonnenhalde, D-

7241 Vespersweiler, Germany [22] Filed: Feb. 16, 1970 [21] Appl. No.: 11,806

[30] Foreign Application Priority Data Primary Examiner-Benjamin A. Borchelt Assistant Examiner-l-l. J. Tudor Attorney-Spencer & Kaye [57] ABSTRACT A method and apparatus for forming a hollow, generally tubular, body of noncylindrical shape from a helically wound strand of a material which will firmly bond to itself upon contact, e.g. a thermoplastic. The strand is continuously deposited, onto and in contact with the last helical winding of the hollow body as the body is being continuously and simultaneously rotated and moved along its longitudinal axis, and the radial distance from the horizontal axis of the hollow body of the point of contact between the deposited strand and the last helical winding is gradually varied in accordance with the desired shape of the body. Simultaneously, the speed of rotation of the hollow body is varied in accordance with the variation of the radial distance of the contact point to maintain the peripheral speed at the contact point constant. A number of specific embodiments of apparatus for forming a body in this manner are disclosed.

22 Claims, 9 Drawing Figures PATENTED FEBZY I975 sum 1 or 8 INVENTOR. Wolfgang Arnold ATTORNEYS.

PATENTEDFEBZYW 3.718.522

SHEET 2 OF 8 INVENTOR. Wolfgang Arnold ATTORNEYS.

PATENTEDFEB271975 3,718,522

SHEET 3 OF 8 IIIIIIIIIlIIIlIIlllIIIIIl/IIIIIIIIIIIIIIIIIII) 31| S L i, 92 k 8 27 Fig. 3

' INVENTOR. Wolfgang Arnold ATTORNEYS.

PATENTEUFEBZTISYE SHEET H 0F 8 PATENTEU F5827 75 SHEET 6 OF 8 jxm.

Fig. 6

INVENTOR. Wolfgang Arnold ATTORNEYS.

PATENTEUFEBZYIW 3,718,522

SHEET 7 BF 8 "2 18 W Hg. 7

INVENTOR Wolfgang Arnold ATTORNEYS.

PMHHEBFEBN 3,718,522

SHEET 8 BF 8 INVEN Wolfgang Arno AT TOR NEYS.

METHOD AND APPARATUS FOR PRODUCING A HOLLOW BODY FROM A HELICALLY WOUND STRAND BACKGROUND OF THE INVENTION The present invention relates to a method and apparatus for producing a hollow, generally tubular, body from at least one helically wound strand of a material, such as a strand of thermoplastic material and/or a strand consisting, e.g., of glass fibers saturated with a hardenable synthetic resin (e.g., polyester) and/or a strand laminated with an adhesive so that the windings of the continuously axially moved hollow body are bonded together by welding and/or molecular interlacing and/or adhesion.

Methods and apparatus for producing cylindrical tubes in a similar manner are known in the art. However, if a tubular body of a shape other than cylindrical is desired, a number of problems arise which render the prior art machines incapable of providing such shapes.

SUMMARY OF THE INVENTION It is the object of the present invention to provide a method and apparatus for forming a tubular body in the manner generally mentioned above with which it is possible to produce, particularly for aesthetic purposes, e.g., the manufacture of lighting fixtures, furniture components, decorative elements and the like, tubular hollow bodies which deviate from the cylindrical shape and/or are not rotationally symmetrical.

This is accomplished according to the present invention in a method of the above-mentioned general type in that the strand of material is caused tobe wound next to or on top of the last helical winding of the hollow body at a spacing from the imaginary longitudinal axis of the rotating hollow body which varies at least temporarily and gradually.

The strandof'material utilized to form the body can be deposited,,o'r fall by as sistance of force of gravity, next to or onto the last helical winding of the hollow body which is rotating with a horizontal axis. Alternatively, it is possible to have the strand fall, by force of gravity, vertically onto the last helical winding of the hollow body while his rotating about a vertical axis.

The apparatus for accomplishing the method comprises at least one source of supply for a strand of material, e.g., an extruder, and/or one coil of material; a rotary and an axial drive means for the hollow body; means changing or varying the point of contact between the deposited strand and the last helical winding of the hollow body dependingon the desired shape of 'thehollow body, alternatingly and gradually in a radial direction toward'and away from the longitudinal axis of the hollow body; anda control means for the rotary drive which varies the speed of the rotary drive depending on the momentary distance of the contact point from the longitudinal axis of the hollow body in such a manner that the peripheral speed of the hollow body at the contact point is approximately constant.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. la is a partially schematic representation of a side "view of a portion of one embodiment of the apparatus according to the invention in a longitudinal section.

FIG. lb illustrates the inclination angles formed by the support rollers of the embodiment of FIG. 1.

FIG. 2 is a partially schematic representation of the remaining portion of the embodiment of the apparatus shown in FIG. 1 in longitudinal section.

FIG. 3 illustrates a control means for varying the radial distance of the strand contact point for the embodiment of the apparatus shown in FIG. 1.

FIG. 4 is a sectional view of a portion of the apparatus according to the invention illustrating a variation of the portion of the apparatus which varies the radial distance of the contact point.

FIG. 5-7 are schematic representations of further variations of the apparatus according to the invention wherein the hollow body is rotated about a vertical axis.

FIG. 8 is a sectional view illustrating a further modification of the apparatus illustrated generally in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the figures in general, all of the embodiments have the following features in common: a device for supplying the strand, i.e., an extruder in the case of a thermoplastic strand, or a feeder device for a strand saturated with a hardenable synthetic or coated with an adhesive (e.g., a roller with a saturation device); a rotary drive for the hollow body; an axial drive for the hollow body to move it away from the strand supply device; means for changing the point of contact of the strand on the last winding of the hollow body depending on the desired shape of the hollow body alternatingly and gradually in a radial direction toward and away from the imaginary longitudinal axis of. the hollow body; and finally a control device which continuously changes the speed of the rotary drive depending on the momentary distance of the contact point from the imaginary longitudinal axis of the hollow body so that the peripheral speed of the hollow body at the contact point is approximately constant at all times. Accordingly, in all figures the same parts or members are indicated by the same reference numerals.

As-shown in FIGS. la and 2, the drive motor 27 drives the intermediate shaft 25 which, via the drive wheel or gear 60, drives the main hollow shaft 2 which is taper bore mounted in bearings l. Firmly connected to the free end of the main shaft 2 for rotating therewith and extending into the hollow body 55 is a block 5. Journaled in'the block 5 is one end of the free arm 9 of a toggle lever on which are mounted the shafts of wheels or gears 8a, 8b, 8c. The other end of the arm 9 is pivotally connected to a rigid support member '11 for an endless belt 54 which rolls on wheels'8c, Extending through the main shaft 2 and coaxial therewith is .a knockout spindle 6. Rotatably mounted on the spindle 6 and axially displaceable along the axis thereof is an element 10 to which is pivotally connected one end of the arm 9 of .a further toggle lever, the other end of the arm 9 being'pivotally connected to the other end of the support member 11. The element 10 is axially supported on the spindle 6 by means of spring 12, pressure plates '62, 63and an abutment formed by nuts 13 threaded onto the end of the spindle 6. Inthis manner the belts-54 are pressed radially outwardly and engage the inner surface of the hollow body 55, causing the body 55 to rotate at the speed of the shaft 2. Since spring 12, its abutment and pressure plates 62 and 63 do not rotate at the same speed as the element which has the same speed as the main shaft 2, it is advisable to insert a pressure bearing 64 between pressure plate 63 and the opposite frontal face of element 10.

The spindle of shaft 6 is driven by the intermediate shaft 25 through the infinitely variable gear box 26 and the drive wheel 61 either through a step-up or stepdown gear action, so that wheels 8a, which in turn drive wheels 8b, 8c and consequently belt 54, are driven by the worm 7 disposed on the spindle 6. A prerequisite for this driie and thus for the operation of the axial drive means, indicated generally by the reference numeral 52, is that the spindle 6 rotate at a different speed than the main shaft 2. By varying the speed difference between shafts 2 and 6 the axial speed of the body 55 resulting from the engagement of the inner walls thereof by the belts 54 can be regulated.

In order to support the free end of the hollow body 55 as it is being axially translated, a cone-shaped member 14 is provided which is rotatably mounted via a bearing 15 on a carriage 16. The carriage 16 is mounted on rails 17 so that it will be moved along with the advancing body 55.

Turning now to the portion of the apparatus for forming the hollow body 55, there is shown receiving plate 30 which is permanently connected with the machine stand by means of mounting member 29. The main shaft 2 and the spindle 6 pass unhampered through plate 30. The plate 30 corresponds with respect to its function to geared scroll lathe chucks. Disposed at the ends of the clamping jaws 31 of the plate 30 are followers 32 which each engage an annular groove 33 of the associated roller bearings 34 which are slidable along shafts 46.

The actual winding process is accomplished by winding rollers 35 which form a support for the deposited strand 4 and of which there are two such rollers in the embodiment of FIG. 1. The winding rollers 35 are driven by wheels 36a, 36b, 36c via a V-belt 37 which runs between the counterbearing wheel 38 and the drive wheel 39. Drive wheel 39 is driven via a flexible shaft 40, V-belt wheel 41, V-belt 42 and V-belt wheel 43 by the infinitely variable geared engine 44. The just described operating unit is provided for each winding roller 35. The drive units are arranged diametrally, or when there are more than two, they are arranged in a circle. Whereas the rollers 35, which are arranged on the circle concentric with the main axis aa, can be brought onto a circle of a greater diameter and vice versa by means of the receiving plate 30, all wheels 41 on disc 45 always maintain their same position. Belt 42 passes over every wheel 41 and is driven by motor 44 via drive wheel 43.

By means of the clamping jaws 31, the rollers 35 can be moved, by sliding them together with their associated bearings 34 along the shafts 46 in order to vary their spacing from the axis a-a. The extreme positions to which the rollers 35 can be moved are indicated by dashed lines 35a and 35b wherein in the position 35b they have a maximum spacing between each other, while in the position 35a, they have a minimum spacing from one another.

Shaft 46 is rotatably mounted in bearings 47 and 48. Connected with the shaft 46 is one end of a lever 49, the other end of which is so mounted in a disk 45 that, when disk 45 is turned slightly in the direction of the arrow with the aid of wheel 50, it causes shaft 46 to be slightly turned by a very narrow sector angle. Bearing 34 slides in a wedge-shaped groove of shaft 46 so that the rollers 35 experience the slight slanting according to FIG. 1b.

The apparatus operates as follows:

The strand 4 forming the hollow body (supporting strand) or a plurality of strands, are fed through one or a plurality of feeders, e.g., feeder 67 (FIG. 3) to the first roller 35 and in particular to the contact point 65. In order to prevent the hollow profile 55, which in this process is not too stable at this time, from being pulled apart by the axial drive 52, the winding rollers 35 are slanted at an angle B so that the developing body is rolled off when transferring from roller to roller, depending on the incline of the windings of the body, at an angle a, which is shown in FIG. 1b. This run-off speed in the axial direction must exactly correspond to the removal speed. Since the hollow profile may still be unstable at this time (hot thermoplastic material, not yet hardened Duroplast) a supporting or spreading element 51, 53 is provided in the axial direction behind the winding member, coaxial with the spindle 6. This spreading element consists of a tubular section 51 placed over the hollow shaft 2 and a plurality of spring arms or spreading arms 53 mounted on and radially extending from the surface of the tubular section 51. These spreading arms 53 may be tensioned by associated springs which are attached at their one end to the tubular section 51 and at the other end to lever arm 142 of the the associated spring arm 53, which is pivotally mounted on a support 141 in a manner so that the spring tension increases with increasing spreading. Although only two of such springs 140 and their associated mountings are illustrated, it is to be understood that each of the spreading arms 53 may be mounted in this manner on the tubular section 51. These spring arms 53 are distributed over the entire periphery of the tubular section 51 in such a manner that they support the profile 55 so that its cross section becomes exactly circular or, if desired, a polygonal shape can be obtained by disposing the spring arms in rows one behind the other. The effect of the supporting element is also substantially influenced by the materials used for the formation of the hollow body 55. When certain materials are used, it may be advisable to support the hollow profile from the inside, in addition to the spreading element 51, 53 or instead thereof, at least in the critical entrance regions, with the aid of an air cushion. A device which blows pressurized air into the airtight or almost air-tight hollow body can be used to provide the air cushion.

FIG. 2 shows the transition from supporting element 51, 53 to the removal belt 54 which is set to the smallest diameter of the hollow body 55 so that it is still able to exert sufficient radial pressure at the inner wall of the hollow body 55 at its point of smallest diameter to enable the hollow body to be carried along. The length of the belt must be so dimensioned that the distance between two adjacent portions of least diameter is easily bridge.

During production it is necessary to have a continuous speed in the individual regions which changes depending on the diameter of the hollow profile. The peripheral speed of the roller 35, however, generally remains constant and is set to an optimal value for the formation of the body (strand formation). Accordingly, if, in the formation of a hollow body 55, the diameter of the winding element consisting of rollers 35 is doubled by increasing their distance from the axis a-a by means of the plate 30 and its associated parts (for example rollers 35 moved to position 35b), then the speed of the main shaft 2 must be reduced to half if, as previously assumed, the speed of rollers 35 can not be doubled.

The speed of the axial drive 52 regulates itself in dependence on the speed of the main shaft 2 since both the shaft 2 and the spindle 6 are driven by the intermediate shaft 25 in the same manner. The advance of the hollow profile per revolution of the main shaft 2, which can be regulated with the infinitely variable gears 26, is thus constant. With the same strand production per unit of time, the speed of the hollow profile 55 must thus be accordingly varied due to its changing diameter. The speed of the drive motor 27 for the main shaft 2 is continuously adapted to this changin g speed.

The angle a must also be adjusted during variation of a the diameter of the body 55 since this angle becomes smaller the greater the distance between rollers35 and vice versa. Control of the plate 30 change of the diameter of the winding element determined by the mutual spacing of the rollers of disk 45, 50 change of angle B) and of the drive motor 30 can be accomplished by stepping motors which themselves are controlled by a cam plate or a perforated tape.

FIG. 3 shows a control arrangement for varying the positions of the rollers 35 which for reasons of clarity was not shown in FIG. 1a. A gear 81 is disposed on the main shaft 2 and meshes with a gear 82 disposed on a shaft 83. Gear 82 drives a worm 85 via the infinitely variable gear box84, which worm meshes with worm gear 86. Connected with the worm gear 86 is a cam plate 87 which is scanned by means of cam follower or roller 88. The roller 88 is disposed at the free end of one arm of a right-angle ball crank 89 which is pivotally mounted on shaft 90. which describes the pitch of the windings of the body 55 and which corresponds with the angle B,)

The arm 89 of the bell crank 89 is provided with an electrical contact device or switch 91 which engages a slit 92 formed in an extension 31' ofjaw 31. The control device operates as follows:

When the arm 89 of the angle moves in the direction toward jaw 31, one contact of the contact device 91 comes in contact with the inner edge of slit 92. The circuit to the electromotor drive 93 for the setting device 94 for the chuck jaws 31 is closed and the device 94 is driven. As a result, the clamping jaws move radially with respect to the axis a-a. This movement is terminated when the contact of the switch 91 lifts off the edge of slit 92 due to the radial movement of the extension 31'.

If, in the course of the curve-dependent control, the free arm 89' is pivoted in the opposite direction, the contact of the switch 91 is pressed to the outer edge of slit 92, so that again a contact is closed. MOtor 93 rotates in the opposite direction. As a result, the clamping jaws 31 move radially outward. This process is terminated when, due to radial movement, the contact lifts off the outer edge of the slit. The distance of rollers 35 from axis a-a and thus the shape of the hollow body is determined by the control profile of the cam plate 87.

In addition to the strand 4 utilized to form the hollow body 55, a plurality of reinforcing or effect strands 4b, 4c, 4d, coming from other subsequently connected producing or feeding devices can be wound onto the hollow body 55 or can be placed axially thereonto as indicated schematically in FIG. 2. If the strand, for example strand 4b, is moved to and fro during operation corresponding to the double-sided arrow b-b, for example in a manner similar to that shown for the strand 4 in FIG. 7, a wavy strand will be spirally wound onto the surface of the hollow body 55 with adjacent strand windings periodically overlapping (diagonal effect). In this manner it is possible to produce a special reinforcing effect or an aesthetic effect, particularly when specially colored strands are employed.

In addition to the effect achieved by the use of a plurality of strands as mentioned above, a further aesthetic effect can be achieved by applying a foil of a material to the outer surface of the hollow body 66. At a rotational speed As shown in FIG. 2, the apparatus for applying such a foil includes a supporting ring 20, which surrounds the hollow body 55 and is rotatably mounted in bearings 22 which, as indicated, are offset by with respect to one another so that it can be driven by a motor at varying speeds. Mounted on the ring 20 are uncoiling devices 21 for a coil of a foil 66. The supporting ring 20 is driven by the intermediate shaft 25 via the step-up gear box 23 so that it receives the proper speed for the application of the foil material 66. At a rotational speed for the supporting ring 20 corresponding to that of the hollow body 55, a foil covering for the hollow profile 55 will result which is parallel in the axial direction. If the rotational speed of the supporting ring 20 is greater or less than the speed of the hollow body 55, a diagonal winding will result. In some cases it may be advantageous or advisable to use a plurality of supporting rings 20, possible with different speeds. If, for example, one or a plurality of strands 4b serving aesthetic purposes are wound onto the strand 4 forming the self-supporting hollow body 55 and/or at least one further strand 4d is wound which serves to further reinforce the hollow profile, it is possible, for example with the uncoiling devices 21, to wind in or insert a foil between two consecutive strands to form an intermediate layer. It is often advisable to wind the effect and/or the reinforcing strand with a pitch that is different from that of the supporting strand 4. Strands 4c, 4d and further following strands can be formed by thermoplastic material or by Duroplasts as well as by profiles, effect materials and reinforcing materials. The arms 126 holding the shafts of rollers 21 are jointed to the supporting ring 20 and are spring tensioned. Consequently, their free end which abuts the surface of the hollow body 55 follows the course of the walls of this hollow body.

Depending on whether the worm 7 has left or righthand turns, the knockout spindle 6 must be provided with a step-up or step-down gear to produce an advance of the hollow profile by means of the axial drive member 52.

Referring now to FIG. 4, there is shown an alternate embodiment for the winding device of FIG. 1 and 2, i.e., for the support means for receiving the deposited strand and the associated mechanisms for varying the radial distance of the contact point from the axis of the hollow body. In the embodiment according to FIG. 4, the drive for the main shaft 2 and the spindle 6 correspond to those of the embodiment of FIGS. 1 and 2. On the main shaft 2 are disposed two coaxial disks 96, 97 which are connected with the main shaft by a V- shaped groove and which rotate therewith. Fastened to the periphery of the disks 96 and 97 in an airtight manner is an elastically expandable belt 98. Belt 98 and disks 96, 97 enclose an air chamber 99 which is connected with a source for pressurized air via a line 110', indicated schematically by the pump 110. When the air pressure in chamber 99 is increased, the elastic belt 98 expands in radial direction so that the maximum diameter of the unit formed by belt 98 and disks 96, 97 is increased. The diameter can also be enlarged in that the disks are brought closer to each other. Conversely, the diameter is reduced when the pressure in the chamber is reduced and/or the disks are spread further apart.

The air pressure in chamber 99 and/or the spacing of the disks 96, 97 is effected in dependence on the desired shape of the hollow body by cam 100 which is driven by the intermediate shaft 25 via an infinitely variable gear box 101. The cam is scanned by a roller 102 which is disposed at the free end of a lever 104 connected with gear 102, which is in engagement with a further gear 103. The axes of both gears 103 and 103 are stationary.

With a pivoting movement of lever 104 both gears turn synchronously about a certain sector angle. With this rotation, levers 105 and 106 change the distance of flanges 107 and 108 and thus the distances of disks 96, 97 from one another. In addition, or if selected, however, the synchronous pivoting movement of the gears 103 and 103 can also be used to operate a throttle valve in the line which connects chamber 99 with the pressure source 110.

In this manner, the distance of the contact point 65 from the imaginary axis (aa) of the hollow body 55 is controlled with the aid of cam 100 depending on the desired configuration of the hollow body.

At the same time and in dependence on the pivoting movement. of gears 103, 103 the speed of the drive motor 27 is changed so that the peripheral speed of the hollow body 55 at the contact point 65 always remains constant. The dependence is symbolized by a dotdashed line 109.

FIG. schematically illustrates a further embodiment of the invention wherein instead of the hollow body 55 being rotated about a horizontal axis as in the FIGS. 1 through 4, the hollow body 55 is disposed to rotate about a vertical axis. The device for changing the contact point 65 in the the radial direction toward and away from the longitudinal axis a--a of the hollow body consists in this case of a drive for horizontally displacing the extruder nozzle producing the strand 4. A control mechanism for carrying out this variation of the contact point 65 is shown in FIG. 7. The strand is directly supported by the last winding of the hollow body. A prerequisite for using this technique is that the previously laid windings have sufficient rigidity to support and maintain the desired shape of the hollow body 55.

The cooling required here is effected by spraying the hollow body in the critical area with water or air of a suitable temperature. The cooling medium comes out of one or a plurality of circularly disposed nozzles 95.

In the embodiment according to FIG. 6, the hollow body is also disposed vertically. The strand 4 coming out of extruder 67 is laid, with the effect of gravity, onto the last winding of the hollow body 55 at contact point to fuse with this last winding. Here, too, rapid stiffening of the thermoplastic material is required to avoid undesirable deformation of the hollow body. This is accomplished in the same manner as for the embodiment of FIG. 5 by cooling (thermoplastic) or heating (Duroplast). The hollow body 55 is held by rollers 69 which both axially and rotatably move the hollow body 55. The shafts of rollers 69 are slightly inclined with respect to the imaginary longitudinal axis aa of the hollow body so that during rotation they effect an advance of the hollow body at its point of contact with the rollers in that they so-to-speak screw it downwardly. Rollers 69 are driven by a motor 111 through a gear 112, 113 and through flexible shafts 114. As with the embodiments of FIG. 5, movement of the extruder and control of the speed of rotation may be as shown in FIG. 7.

In the embodiment of FIG. 7 the axis of the hollow body 55 also extends vertically. Strand 4 which comes out of extruder 67 places itself, under the effect of gravity, vertically onto the last winding of the hollow body at the point of contact 65. The hollow body 55 is supported along its base by the lowerable supporting plate 68 which moves helically downward during rotation. Consequently the strand is immersed into the cooling medium 116 (e.g., water) in container 117 soon after being placed on the hollow body and becomes stiff. The shaft 118 of plate 68 is driven with the aid of electromotor 119. The extruder 67 disposed above the hollow body is horizontally movable by means of a carriage 124 in order to vary the distance of the contact point 65 from the axis aa. The horizontal movement of the extruder 67 is controlled with the aid of cam plate 121. The control curve of this cam plate corresponds to the desired noncircular or rotationally symmetrical configuration of the hollow body 55 to be produced. The cam plate 121 acts on the extruder 67 through a lever system 120, 122, 123, and a further arm 124 is jointed to the free arm of the two-armed lever 122, with which the speed of the drive motor 119 can be controlled. This speed is thus changed in dependence on the horizontal movement of the extruder in such a manner that in each position of the extruder 55, i.e., at each arbitrary distance of the contact point 65 from axis a-a, the peripheral speed of the hollow body 55 at the contact point 65 is approximately equal.

FIG. 8 shows a further example of a device in the form of a winding element for changing the contact point of the strand 4 on the last winding of the winding element in the direction toward the imaginary axis of the hollow body and away therefrom. The jacket of the roller-shaped winding element is formed by a ring of laminations or bars 70. Each of the bent bars 70 has a starting section 70 which together form the cylindrical working surface of the winding element onto which the strand is deposited. The remaining portion of each bar 70 serves to control the position of its section 70 In the control portion 70" the laminations are each mounted on a pivot axis 120. The pivot axes are supported by the base of a profiled member 71 having a U- shaped cross section. The two U bars of the profiled element enclose an acute angle toward its base and engage in respective bores of control elements 72 and 73. The two annular profiled elements 72, 73 are axially displaceably mounted on the main shaft 2, each with a V-shaped groove, and consequently rotate together with the shaft 2.

In order to demonstrate the kinematics of the control, the upper half of the drawing shows the one-piece profiled elements 72 and 73 with maximum mutual approximation and the lower half shows them at the maximum distance, which elements in reality are both at the same axial height. Grooved rings 74 and 75 each enclose a flange '72" or 73 of the profiled elements. The grooved rings are joined to the arms of a twoarmed lever 77 by means of rods 76 and 80, the pivot axis 78 of the lever being permanently connected with the machine stand.

At the rear of the laminations 70 there are disposed rollers 81 whose axes enclose a wide angle with respect to the main shaft 2. The rollers 81 extend with their periphery into the circular path of movement of the laminations or bars 70. When the entire winding element is rotated by means of shaft 2,the rearward free ends of the laminations 70 consecutively move onto the adjacent roller 81 and immediately thereafter slide off therefrom. In this process the respective lamination or bar 70 is slightly pivoted around its axis 130 and when the roller has slid off, the lamination flips back into its starting position under the influence of spring 83. Under the influence of the rollers 81, the laminations 70 which are provided with longitudinal holes 131 simultaneously experience a longitudinal movement so that they perform a somewhat elliptical movement in section 70' during the pivoting process. This movement has the result that the strand 4 placed on the working surface 70' of the laminations is rhythmically lifted and moved in the axial direction.

Levers 77 are controlled by a cam plate (not shown) depending on the desired configuration of the hollow body to be produced. The camming mechanism and speed control arrangement may however be similar to that shown in FIG. 3. In the course of the pivoting movements of the two-armed levers 77, the profiled pieces 73, 72 are moved toward one another and away from one another via push rods 76 and 80 and grooved rings 74, 75. With this movement of the profiled pieces the U-shaped pieces 71 are moved radially outwardly or inwardly depending on the control effected due to the obliqueness of their arms, so that the contact point 65 of the strand 4 approaches the longitudinal axis of the hollow body or is removed therefrom.

In the embodiments having a vertically disposed hollow body (FIGS. 5-7) it is necessary in each case to soon cool the thermoplastic strand 'or to heat the strand saturated with a hardenable synthetic. Special devices to stiffen the placed strand by cooling or heating may also be provided, however, with hollow bodies rotating about a horizontal axis, if desired.

In the embodiments having a vertically disposed hollow body, i.e., FIGS. 5-7, a thermoplastic strand is preferably processed since in many cases cooling produces a simpler and faster stiffening. With the exception of the embodiment according to FIG. 7, all embodiments produce an endless tubular hollow body of whose free end there are continuously cut off sections of the desired length as semifinished products for the manufacture of lighting fixtures, decorative objects and the like.

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

I claim:

1. An apparatus for forming a structurally rigid free standing and endless elongated hollow body from a helically wound strand of thermoplastic material of the type which will cause adjacent windings of the strand to bond together, comprising in combination:

(a) means for continuously supplying a strand of said material and for depositing said strand adjacent to and contacting the last helical winding of the hollow body with the point of initial contact between the strand being supplied and the last winding of the hollow body being stationary in the direction of the longitudinal axis of the hollow body the sufficiently hardened last winding of the hollow body constituting at least in sections the support for the supplied, soft and bondable strand;

(b) a rotary drive means;

(c) means coupled to said rotary drive means for continuously rotating the hollow body and for continuously moving the hollow body along its longitudinal axis in a direction away from said strand supplying means; and,

(d) controllable means for gradually varying, in

either direction, the radial distance from the longitudinal axis of the hollow body of said point of contact between said supplied strand and the last winding of the hollow body in an arbitrary and random manner during operation of the apparatus, whereby said point of contact can be varied at any given instant and an endless hollow body of arbitrarily varying radial dimensions and of desired configuration is formed.

2. The apparatus defined in claim 1 wherein said means for rotating the hollow body rotates it about a horizontal axis; and wherein said means for varying the radial distance of the contact point includes at least one pair of diametrally mounted substantially horizontal members unto which said strand is deposited, and means for gradually varying the radial distance of said members from said horizontal axis whereby the radial distance of said contact point is varied.

3. The apparatus defined in claim 2 wherein said members comprise rotatably driven rollers and wherein said means for varying the distance between said members comprises a geared scroll lathe chuck device.

4. The apparatus defined in claim 3 including means for inclining the shafts of said rollers with respect to the longitudinal axis of the hollow body in a horizontal plane parallel to the plane of the longitudinal axis.

5. The apparatus defined in claim 3 wherein the axles of said rollers are inclined with respect to the longitudinal axis of the hollow body in a vertical plane passing through said longitudinal axis.

6. The apparatus defined in claim 4 wherein the axles of said rollers are also inclined with respect to the longitudinal axis of the hollow body in a vertical plane passing through said longitudinal axis.

7. The apparatus as defined in claim 1 wherein said means for rotating the hollow body rotates it about a horizontal axis; and wherein said means for varying the radial distance of the contact point includes an elastically expandable member onto the outer surface of which the strand is deposited, said member enclosing a chamber, and a source of air for pressurizing said chamber to expand said member.

8. The apparatus as defined in claim 7 wherein said means for varying the radial distance of said contact point further includes a pair of disks slidably mounted on a horizontal shaft coaxial with the said longitudinal axis of the hollow body, said expandable member being connected between the periphery of said disks to enclose a chamber around said shaft, and means for varying the distance between said disks, whereby the diameter of said chamber is varied.

9. The apparatus defined in claim 1 wherein said means for rotating the hollow body rotates it about a horizontal axis, and said means for varying the radial distance of the contact point includes a plurality of thin bar-like members arranged to form a ring, and means for varying the diameter of said ring.

10. The apparatus defined in claim 9 wherein said members are hingedly mounted to form two-armed levers, and means engaging one of the arms of each member for continuously imparting a limited pivoting movement and a simultaneous rhythmic axial movement to said members.

11. The apparatus as defined in claim 10 wherein said ring of members is rotated by said rotary drive means at the same speed as the hollow body.

12. The apparatus defined in claim 1 wherein said means for rotating the hollow body rotates it about a vertical axis and wherein said means for varying the radial distance of the contact point comprises means for moving said strand supplying means in a horizontal direction.

13. The apparatus as defined in claim 12 wherein formed from a thermoplastic material, and means for cooling said strand are disposed adjacent said contact point.

14. The apparatus as defined in claim 12 wherein said means for rotating the hollow body comprises a rotating disk'which supports the free end of the vertically disposed hollow body, said disk being mounted so that it can be gradually lowered as it is rotated.

15. The apparatus as defined in claim 12 wherein the vertically rotating hollow body is held by means of a plurality of rollers which can continuously move the hollow body downward as it is being rotated, said rollers being inclined with respect to the longitudinal axis of the hollow body.

16. The apparatus as defined in claim 1 wherein said means for rotating and axially moving the hollow body comprises: a hollow shaft coupled to said rotary drive means and coaxial with the longitudinal axis of the hollow body; a plurality of elon ated drive belts, each of said drive belts being moun ed on a pair of pulleys whose axes are in a plane transverse to said hollow shaft; mounting means for said pulleys connected to said hollow shaft for rotation therewith, said mounting means including means for pressing said drive belts radially outward from the axis of said hollow shaft so that said drive belts engage the inner surface of the hollow body, thereby causing the hollow body to rotate; a drive shaft extending through the center of said hollow shaft, and rotating at a speed different from that of said hollow shaft; a worm disposed on said drive shaft; and at least one worm gear in engagement with said worm for rotating said drive belts about said pulleys, thereby causing said drive belts to move the hollow body in an axial direction.

17. The apparatus defined in claim 16 wherein each of said mounting means for said pairs of pulleys comprises a pair of oppositely disposed toggle levers, said pulleys being mounted on the free lever arms thereof, the toggle joint of one of said toggle levers being fixedly supported on said hollow shaft and the toggle joint of the other of said toggle levers being resiliently supported on said shaft in a manner whereby it is axially movable along said shaft.

18. The apparatus as defined in claim 1 including a rotatably mounted support ring encircling the hollow body, means for rotating said ring, and means carried by said ring for uncoiling a foil from a roll and applying it to the outer surface of the hollow body.

19. The apparatus defined in claim 11 wherein said means for rotating the hollow body rotates it about a horizontal axis; and wherein means are provided within the hollow body and engaging the inner surface thereof for supporting said hollow body in its desired configuration.

20. The apparatus as defined in claim 19 wherein said means for supporting said hollow body comprises a tubular element mounted on a shaft which is coaxial with the longitudinal axis of the hollow body, and a plurality of radially extending resilient arms mounted on said tubular element, the free ends of said arms engaging and supporting the hollow body.

21. The apparatus as defined in claim 20 wherein springs are provided between said resilient arms and said tubular element in such a manner that the spring tension increases with increased spreading of the arms.

22. The apparatus defined in claim 1 further comprising a control means for varying the speed of said rotary drive means in accordance with the radial distance of said contact point from the longitudinal axis of the hollow body so as to maintain a constant peripheral speed for the hollow body at said contact point. 

1. An apparatus for forming a structurally rigid free standing and endless elongated hollow body from a helically wound strand of thermoplastic material of the type which will cause adjacent windings of the strand to bond together, comprising in combination: (a) means for continuously supplying a strand of said material and for depositing said strand adjacent to and contacting the last helical winding of the hollow body with the point of initial contact between the strand being supplied and the last winding of the hollow body being stationary in the direction of the longitudinal axis of the hollow body the sufficiently hardened last winding of the hollow body constituting at least in sections the support for the supplied, soft and bondable strand; (b) a rotary drive means; (c) means coupled to said rotary drive means for continuously rotating the hollow body and for continuously moving the hollow body along its longitudinal axis in a direction away from said strand supplying means; and, (d) controllable means for gradually varying, in either direction, the radial distance from the longitudinal axis of the hollow body of said point of contact between said supplied strand and the last winding of the hollow body in an arbitrary and random manner during operation of the apparatus, whereby said point of contact can be varied at any given instant and an endless hollow body of arbitrarily varying radial dimensions and of desired configuration is formed.
 2. The apparatus defined in claim 1 wherein said means for rotating the hollow body rotates it about a horizontal axis; and wherein said means for varying the radial distance of the contact point includes at least one pair of diametrally mounted substantially horizontal members unto which said strand is deposited, and means for gradually varying the radial distance of said members from said horizontal axis whereby the radial distance of said contact point is varied.
 3. The apparatus defined in claim 2 wherein said members comprise rotatably driven rollers and wherein said means for varying the distance between said members comprises a geared scroll lathe chuck device.
 4. The apparatus defined in claim 3 including means for inclining the shafts of said rollers with respect to the longitudinal axis of the hollow body in a horizontal plane parallel to the plane of the longitudinal axis.
 5. The apparatus defined in claim 3 wherein the axles of said rollers are inclined with respect to the longitudinal axis of the hollow body in a vertical plane passing through said longitudinal axis.
 6. The apparatus defined in claim 4 wherein the axles of said rollers are also inclined with respect to the longitudinal axis of the hollow body in a vertical plane passing through said longitudinal axis.
 7. The apparatus as defined in claim 1 wherein said means for rotating the hollow body rotates it about a horizontal axis; and wherein said means for varying the radial distance of the contact point includes an elastically expandable member onto the outer surface of which the strand is deposited, said member enclosing a chamber, and a source of air for pressurizing said chamber to expand said member.
 8. The apparatus as defined in claim 7 wherein said means for varying the radial distance of said contact point further includes a pair of disks slidably mounted on a horizontal shaft coaxial with the said longitudinal axis of the hollow body, said expandable member being connected between the periphery of said disks to enclose a chamber around said shaft, and means for varying the distance between said disks, whereby the diameter of said chamber is varied.
 9. The apparatus defined in claim 1 wherein said means for rotating the hollow body rotates it about a horizontal axis, and said means for varying the radial distance of the contact point includes a plurality of thin bar-like members arranged to form a ring, and means for varying the diameter of said ring.
 10. The apparatus defined in claim 9 wherein said members are hingedly mounted to form two-armed levers, and means engaging one of the arms of each member for continuously imparting a limited pivoting movement and a simultaneous rhythmic axial movement to said members.
 11. The apparatus as defined in claim 10 wherein said ring of members is rotated by said rotary drive means at the same speed as the hollow body.
 12. The apparatus defined in claim 1 wherein said means for rotating the hollow body rotates it about a vertical axis and wherein said means for varying the radial distance of the contact point comprises means for moving said strand supplying means in a horizontal direction.
 13. The apparatus as defined in claim 12 wherein formed from a thermoplastic material, and means for cooling said strand are disposed adjacent said contact point.
 14. The apparatus as defined in claim 12 wherein said means for rotating the hollow body comprises a rotating disk which supports the free end of the vertically disposed hollow body, said disk being mounted so that it can be gradually lowered as it is rotated.
 15. The apparatus as defined in claim 12 wherein the vertically rotating hollow body is held by means of a plurality of rollers which can continuously move the hollow body downward as it is being rotated, said rollers being inclined with respect to the longitudinal axis of the hollow body.
 16. The apparatus as defined in claim 1 wherein said means for rotating and axially moving the hollow body comprises: a hollow shaft coupled to said rotary drive means and coaxial with the longitudinal axis of the hollow body; a plurality of elongated drive belts, each of said drive belts being mounted on a pair of pulleys whose axes are in a plane transverse to said hollow shaft; mounting means for said pulleys connected to said hollow shaft for rotation therewith, said mounting means including means for pressing said drive belts radially outward from the axis of said hollow shaft so that said drive belts engage the inner surface of the hollow body, thereby causing the hollow body to rotate; a drive shaft extending through the center of said hollow shaft, and rotating at a speed different from that of said hollow shaft; a worm disposed on said drive shaft; and at least one worm gear in engagement with said worm for rotating said drive belts about said pulleys, thereby causing said drive belts to move the hollow body in an axial direction.
 17. The apparatus defined in claim 16 wherein each of said mounting means for said pairs of pulleys comprises a pair of oppositely disposed toggle levers, said pulleys being mounted on the free lever arms thereof, the toggle joint of one of said toggle levers being fixedly supported on said hollow shaft and the toggle joint of the other of said toggle levers being resiliently supported on said shaft in a manner whereby it is axially movable along said shaft.
 18. The apparatus as defined in claim 1 including a rotatably mounted support ring encircling the hollow body, means for rotating said ring, and means carried by said ring for uncoiling a foil from a roll and applying it to the outer surface of the hollow body.
 19. The apparatus defined in claim 11 wherein said means for rotating the hollow body rotates it about A horizontal axis; and wherein means are provided within the hollow body and engaging the inner surface thereof for supporting said hollow body in its desired configuration.
 20. The apparatus as defined in claim 19 wherein said means for supporting said hollow body comprises a tubular element mounted on a shaft which is coaxial with the longitudinal axis of the hollow body, and a plurality of radially extending resilient arms mounted on said tubular element, the free ends of said arms engaging and supporting the hollow body.
 21. The apparatus as defined in claim 20 wherein springs are provided between said resilient arms and said tubular element in such a manner that the spring tension increases with increased spreading of the arms.
 22. The apparatus defined in claim 1 further comprising a control means for varying the speed of said rotary drive means in accordance with the radial distance of said contact point from the longitudinal axis of the hollow body so as to maintain a constant peripheral speed for the hollow body at said contact point. 